PTL 1 (International Publication No. 2006-111445) discloses a reading device for reading an identification tag which is applied to a top portion surface of a tray. The reading device is provided with a tray, a drawer which supports the tray, a tray tower which accommodates multiple drawers, and a tag reader which reads an identification tag. Electric components to be mounted to a circuit board are held in the tray. The tag reader is mounted to the front side (the drawer side of the tray) of the tray tower and the reading direction of the tag reader is the downward direction. By pulling out the drawer which is accommodated in the tray tower from the tray tower, the identification tag on the tray which is pulled out passes under the tag reader. Accordingly, the tag reader reads the identification tag on the tray.